1. Field of the Invention
The present invention relates to a radiographic system which performs automatic exposure control, a drive control method for a radiographic system, a drive control program and a radiological image detection device.
2. Description of the Related Art
In the medical field, an X-ray radiographic system that uses radiation such as X-rays is known. The X-ray radiographic system includes an X-ray generation device which generates X-rays and an X-ray radiographic device which receives X-rays and radiographs an X-ray image. The X-ray generation device has an X-ray source which irradiates a subject with X-rays, a radiation source control device which controls the driving of the X-ray source and an irradiation switch for inputting an X-ray irradiation start instruction. The X-ray radiographic device has an X-ray image detection device which receives X-rays that have passed through the subject and detects an X-ray image and a console which controls the driving of the X-ray image detection device.
In the X-ray radiographic system field, recently, an X-ray image detection device using a flat panel detector (FPD) as a detection panel has been commonly used instead of an X-ray film or an imaging plate (IP). The FPD has pixels which accumulate signal charge according to a reached X-ray dose and are arranged in a matrix shape. The FPD accumulates the signal charge in every pixel and the accumulated signal charge is converted to a voltage signal by a signal processing circuit so as to detect an X-ray image showing the image information of the subject and output the image as digital image data.
An electronic cassette (portable X-ray image detection device) in which the FPD is built in a rectangular parallelepiped-shaped case has also been put to practical use. Unlike a fixed type cassette which is fixed to a radiographic stand and cannot be removed from the radiographic stand, the electronic cassette is used by being detachably attached on an existing radiographic stand for a film cassette or an IP cassette and on an exclusive radiographic stand, and is used by being disposed above a bed or making the subject themself hold the cassette to radiograph a region in which radiography is difficult in the fixed type cassette. In addition, the electronic cassette is taken out of a hospital and used in a place where radiographic stand facilities are not present in some cases to radiograph the elderly convalescing at home, and an emergency patient due to an accident, a disaster or the like.
Moreover, a radiation dose detection sensor which detects the radiation dose of the X-rays that have passed through a subject is provided, and when an integrated value (accumulated radiation dose) of the radiation dose detected by the radiation dose detection sensor reaches a threshold value set beforehand, X-ray irradiation from the X-ray source is stopped and automatic exposure control (AEC) which makes the transition from an accumulation operation to a reading operation is performed in the X-ray image detection device.
An X-ray apparatus which includes a radiation dose detection sensor (light receiving unit) that detects a passed X-ray dose and an AEC unit (phototimer circuit) that determines an X-ray irradiation stop by comparing a detection result of the radiation dose detection sensor and a threshold value (reference value) is disclosed in JP1990-021597A (JP-H02-021597A). When the detection result of the radiation dose detection sensor reaches the threshold value, an X-ray cutoff request signal is output. The radiation source control device receives the X-ray cutoff request signal to stop the X-ray irradiation. In addition, a radiation dose detection sensor which transmits an irradiation stop signal to a radiation source control device (X-ray irradiation device) wirelessly and an AEC unit (phototimer) are disclosed in JP2006-068507A.